• Geophysics and Geophysical Exploration
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• v.16 no.2
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• pp.97-105
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• 2013

Nuclear magnetic resonance (NMR) logging has become an important technique for formation evaluation, detecting interaction signals between H protons and applied magnetic fields. Measured decay signals called relaxation, contain important information about density of H protons and different decay rate due to its fluid type in the sensitive area. Thus, petrophysical information such as porosity, permeability and wettability can be estimated through the interpretation of the decay signals. Many researches on random walk simulation have been published, since a simulation method based on random walk for solving exponential decays was adapted in the early of 1950. This study first makes a review on NMR simulation researches, explains two most important methods: simulation with or without considering magnetic field gradient. Lastly, the study makes a comparison between NMR simulation responses with and without magnetic field gradient to show the importance to consider magnetic gradient to analyze the effects of magnetic gradients on NMR responses.

• Journal of the Korean Magnetic Resonance Society
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• v.19 no.2
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• pp.95-98
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• 2015

Reverse gyrase is a hyperthermophile specific protein which introduces positive supercoils into DNA molecules. Reverse gyrase consists of an N-terminal helicase-like domain and a C-terminal topoisomerase domain. The helicase-like domain shares the three-dimensional structure with two tandem RecA-folds (H1 and H2), in which the subdomain H2 is interrupted by the latch domain (H3). To understand the physical property of the hyperthermophile-specific protein, two subdomains af_H1 and af_H23 have been cloned into E. coli expression vector, pET28a. The $^{15}N$-labeled af_H1 and af_H23 proteins were expressed and purified for heteronuclear NMR study. The af_H1 protein exhibits the well-dispersion of amide signals in its $^1H/^{15}N$-HSQC spectra and thus further NMR study continues to be progressed.

• Journal of the Korean Magnetic Resonance Society
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• v.19 no.1
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• pp.36-41
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• 2015

The causative agent of shigellosis, Shigella flexneri, is a Gram-negative anaerobic bacterial pathogen that causes one of the most infectious bacterial dysenteries in humans. It originates infection by invading cells of the colonic epithelium using a type III secretion system. Despite S. flexneri is closely linked with the human disease, structural study is very deficient. Here, we have initiated NMR study of SF1002 which is the uncharacterized protein from S. flexneri strain 5a M90T. Based on a series of triple resonance spectra, sequence-specific assignments of the backbone amide resonances of SF1002 could be completed. This NMR study would contribute to the structural genomics of S.flexneri.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.591-594
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• 2008

지구 온난화 문제의 심각성이 대두되면서 이산화탄소 저감 기술에 대한 관심이 증폭되고 있다. 가장 이상적인 방법은 탄소가 포함되지 않은 청정 재생 에너지원이지만, 에너지 공급 규모 면에서 보면 근미래에도 화석 연료가 에너지 수요에 대한 주요 공급원으로 남아있을 것이라는 의견이 지배적이다. 많은 화석 연료 중 천연가스는 탄소 배출량이 가장 적은 청정 연료로 지난 10년간 수요가 폭발적으로 증가해왔다. 이를 고려해볼 때 탄소 배출량이 적은 천연가스를 생산하면서 이산화탄소를 격리 시킬 수 있는 기술은 매우 매력적이다. 본 연구에서는 심해저의 메탄 하이드레이트로 부터 천연가스를 생산하는 기술로서 이산화탄소와 질소의 혼합 가스를 사용하는 기술 개발의 일환으로 혼합 가스에 의한 메탄 하이드레이트 해리 속도를 $^{13}C$ NMR을 이용해 측정한 결과를 제시하고자 한다.

• Journal of the Korean Magnetic Resonance Society
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• v.10 no.1
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• pp.38-45
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• 2006

The NMR and MS techniques were applied to identification and quantitative analysis of oligomers in a commercialized poly (trimethylene terephthalate). Oligomers in a commercialized poly (trimethylene terephthalate) were extracted via a dissolving and reprecipitation method. Analysis of the components of the extract using NMR and MS revealed that it contained mainly cyclic oligomers with degrees of polymerization of 2, 4 and 5 (dimer, tetramer and pentamer). Trimer and cyclic oligomers with degrees of polymerization of more than 6 were not found in the extract in the present study. Quantitative analysis of dimer was performed by NMR spectroscopy.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.146.2-146.2
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• 2011

Molecular behaviors and crystal structures of the binary hydrates of $CH_4$ and ethanol were identified by means of 13C solid-state NMR and powder XRD methods at various concentrations of ethanol. In addition, NMR peak areas were used to calculate cage occupancies for both guest species. Obtained results showed that more $CH_4$ molecules are captured into hydrate phase per unit mass of ethanol molecules because $CH_4$ molecule can occupy sII large cages more, and pure $CH_4$ hydrate can form more as well at lower ethanol concentrations. Even though tuning phenomenon was already reported for some aqueous hydrate promoters such as THF, aqueous ethanol solutions are found to play the same tuning role in the binary clathrate hydrates in this study.

• Journal of the Korean Magnetic Resonance Society
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• v.15 no.2
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• pp.104-114
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• 2011

Rapid exchange and hydrolysis of the tubulin-bound guanine nucleotides have been known to govern the dynamics of microtubules. However, the instability and low concentration have made it difficult for the microtubule-bound GTP to be observed directly. In this study, we circumvent these problems by lyophilization and using cross-polarization techniques. $^{31}P$ NMR signals were detected from the tubulin-bound GTP in microtubules for the first time. Analysis of the $^{31}P$ CPMAS NMR spectrum indicates that GTP hydrolysis was delayed by the presence of taxol.

• Journal of the Korean Magnetic Resonance Society
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• v.15 no.2
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• pp.90-103
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• 2011

Cornus officinalis (Cornaceae) is primarily grown in Asian countries. The pericarp of C. officinalis (Corni Fructus) is a well-known traditional medicine with tonic, analgesic, and diuretic properties. We analyzed methanolic extracts of Corni Fructus (grown in Korea and China) by $^1H$ NMR spectroscopy. Metabolite profiling was performed to characterize the metabolic difference between different Corni Fructus origins (Korea or China). Principal components analysis revealed significant separation between Comus Fructus from different origins. The metabolites responsible for differences were identified using loading plots, coefficients plots, and variable influence on projection followed by t-tests. As a result, 16 metabolites were identified and quantified; tyrosine, acetate, sucrose, and malate differed the most between origins. These data suggest that NMR-based metabolomics can be used to identify differences between Corni Fructus samples obtained from different regions.

• Journal of the Korean Magnetic Resonance Society
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• v.24 no.2
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• pp.47-52
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• 2020

Liquid-liquid phase separation (LLPS) of biomolecules, a newly-found phase behavior of molecules in the liquid phase, has shown to its relationship to various biological function and misfolding diseases. Extensive studies have increasingly revealed a general mechanism of LLPS and characterized the liquid droplet; ho wever, intermolecular interactions of proteins and structural states of LLPS-inducing proteins inside of the droplet remain largely unknown. Solution NMR spectroscopy has emerged as a powerful approach as it provides invaluable information on protein intermolecular interactions and structures at the atomic and residue level. We herein comprehensively address useful techniques of solution NMR including the effect of paramagnetic relaxation enhancement for the study on the LLPS and droplet based on recent studies.

• Journal of the Korean Magnetic Resonance Society
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• v.24 no.2
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• pp.43-46
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• 2020

Huntington's disease (HD) is an inherited neurodegenerative disease caused by abnormal polyglutamine (polyQ) expansion in the huntingtin protein (Htt). There is no cure for HD so far. Although exact molecular mechanism of HD pathogenesis is still elusive, fibril formation of the expanded Htt is linked to the toxicity. In this study, we prepared the expanded Htt containing 46 glutamines, and induced the fibrillation by proteolytic cleavage. Fibrillation of the pathogenic Htt has been monitored by time course NMR experiment. The NMR-based monitoring method could be widely used to screen the candidates to inhibit the fibrillation of the pathogenic Htt.